1. Field of the Invention
The present invention relates to a power window apparatus of an automobile and a method for controlling the same, more specifically, to a power window apparatus provided with a control part for detecting pinching when a foreign matter is pinched in a window so as to stop or operate the opening and closing operation of the window in reverse and a method for controlling the same.
2. Description of the Prior Art
There has been proposed a power window apparatus for use in an automobile which opens and closes a window by its driving part. The power window apparatus is provided with a control part. When a foreign matter is pinched in a window at the time of opening and closing the window, the control part determines whether there is pinching in the window to prevent an excessive load from being applied to the driving part and to protect the pinched matter. In the event that there is pinching, the control part immediately stops or operates the driving part in reverse.
Such a prior art power window apparatus, as shown in the construction of FIG. 5, has a driving part capable of being operated in forward or reverse for opening and closing a window (hereinafter referred to as a xe2x80x9cmotorxe2x80x9d) 41, a power supply part 42 for supplying power to the motor 41, an operation switch part 43 having a plurality of switches and outputting a voltage as a signal for opening and closing the window by manual operation, a control part 44 (hereinafter referred to as a xe2x80x9cCPUxe2x80x9d) for controlling the rotation of the motor 41 through the motor power supply part 42 corresponding to the operation of the operation switch part 43, and a pulse generation part 45 for generating a pulse corresponding to the rotation of the motor 41.
When any one of the switches (43a, 43b, 43c and 43d) of the operation switch part 43 is operated, a signal corresponding to the switch operated is inputted to the input terminals (P02, P03 and P04) of the CPU 44. The CPU 44 outputs a signal from the output terminals (P05 and P06) to the power supply part 42 in accordance with the signal inputted. The motor power supply part 42 supplies power to the motor 41 corresponding to the signal inputted. The motor 41 is rotated in forward/reverse so as to open/close the window.
FIG. 2 is a characteristic diagram showing one example of the number of pulses generated, a reference value of a motor torque value, a tolerance value for tolerating the fluctuation in the motor torque value, and a determination value provided by adding the reference value and the tolerance value for determining pinching, which are set for each block when the whole travel region of the window is divided into 36 blocks in the power window apparatus. The vertical axis shows the torque value outputted by the motor 41 (kgxc2x7f), and the horizontal axis shows the number of pulses generated by the pulse generation part 45 (the left end shows the window full-open position and the right end shows the window full-close position). The respective set values are set previously and stored in a storing part 44b in the CPU 44.
In the construction described above, when the motor 41 is rotated, the pulse generation part 45 is interlocked with the rotation of the motor 41 to generate a pulse, and outputs the pulse to the input terminal P07 of the CPU 44.
At this time, the CPU 44 measures the time required for the interval between the inputted pulses generated, detects a motor torque value based on the time measured, counts the number of the inputted pulses generated, and from the number of the pulses generated, determines in what block the window is positioned.
The CPU 44 compares the determination value in the block stored in the storing part 44b and determined with the motor torque value detected. When the motor torque value is larger than the determination value, the CPU 44 determines that a foreign matter is pinched in the window to stop or reverse the motor 41.
Such a power window apparatus sets the determination value for each block. The region required for the storing part 44b in the CPU 44 is {fraction (1/32)} times smaller than that when the determination value is set for each pulse. There occur a fluctuation in the motor torque value or a fluctuation in the coefficient of friction between the window and the window frame due to temperature changes, and an irregular variation in the pulse outputted owing to the shaved gear teeth of the pulse generation part 45 due to changes over time, so that the motor torque value detected is varied in the same block each time a pulse is generated. In some cases, the variation in the motor torque value may exceed the tolerance value. In addition, the power window apparatus may determine that there is pinching when the pinching does not occur, so as to cause malfunction to stop or reverse the operation of the window.
The present invention solves this problem, and an object of the present invention is to provide a power window apparatus and a method for controlling the same, which are less likely to cause malfunction to determine that there is pinching when the pinching does not occur, thereby stopping or reversing the operation of the window in the event that a motor torque value is fluctuated in the small storing part due to temperature changes or changes over time.
To solve the foregoing problem, a power window apparatus of the present invention comprises a driving part for opening and closing the window of an automobile, a pulse generation part for generating a pulse corresponding to the operation of the driving part, torque value detection means for detecting a torque value outputted by the driving part, torque value storing means for storing a reference value of torque and a first determination value larger than the reference value for each block of a plurality of blocks dividing the whole travel range of the window, and a control part for comparing the torque value detected during the operation of the driving part with a first determination value of the block in which the window is positioned at that time each time the pulse is generated, so as to determine pinching when the torque value is larger than the first determination value and to stop or operate the driving part in reverse, wherein the control part, only when the torque value is larger than a reference value of the block in which the window is positioned, adds a correction value in proportion to a difference between the torque value and the reference value to the first determination value so as to provide a second determination value, thereby, at the time of the next detection of the torque value, determining pinching when the torque value in generating the pulse is larger than the second determination value.
According to the present invention, when the torque value detected is varied due to temperature changes or changes over time, a value in proportion to the variation is added to the determination value at the time of the next detection for determination. It is possible to provide a power window apparatus which is less likely to cause malfunction to determine that pinching occurs when the pinching does not occur, thereby stopping or reversing the operation of the window.
According to the present invention, a method for controlling a power window apparatus comprises the steps of: storing a reference value of torque outputted by a driving part for opening and closing the window and a first determination value larger than the reference value for each block of a plurality of blocks dividing the whole travel range of the window of an automobile; detecting a torque value each time the window travels a predetermined distance in the block; comparing the torque value with a first determination value of the block in which the window is positioned at that time; determining pinching when the torque value is larger than the first determination value; and outputting a control signal for stopping or operating the window in reverse, the method further comprises the steps of: obtaining a difference between the torque value and the reference value of the block in which the window is positioned; and adding a correction value in proportion to the difference to the first determination value of the block in which the window is positioned only when the difference is positive to obtain a second determination value, thereby, at the time of the next detection of the torque value, determining pinching when the torque value is larger than the second determination value.
The present invention can provide a method for controlling a power window apparatus which is less likely to cause malfunction, as described above.
According to the present invention, the correction value does not exceed a predetermined value.
According to the present invention, the correction value does not exceed a predetermined value. Thus, when the torque value detected is increased gradually, the determination value is not increased endlessly. When pinching occurs, the pinching can be determined correctly.
According to the present invention, the correction value is 25% of the difference, and the predetermined value is 25% of a difference between the first determination value and the reference value of the block.
According to the present invention, the correction value is 25% of the difference, and the predetermined value is 25% of a difference between the first determination value and the reference value of the block in which the window is positioned. Thus, the control part facilitates calculation so as to perform calculation fast, or it is possible to use the control part which is inexpensive although the calculation performance is poor.